When is a pint not a pint? When it's a social-media experience. Guinness's latest innovation is a glass whose design becomes a QR code when filled with the black stuff.
Gimmicky, but cool. By running your smartphone's reader over the code it allows you to unlock, then update your "Guinness pint-drinking status" on Facebook and get money-off coupons.
A new trend, then, or the dregs at the bottom of the ad department's glass?